Method and apparatus for handling fermentation gas



Dec. 22, 1953 F. A. CRAIG METHOD AND APPARATUS FOR HANDLING FDRMENTATIDN GAS Filed July 19, 1951v l5 sheets-sheet 1 F. A. CRAIG Dec. 22, 1953 METHOD AND APPARATUS FOR HANDLING FERMENTATION GAS 3 Sheets-Shes?I 2 Filed July 19, 1951 INVENTOR. Mfyw; OWWSyS.

A QN f F. A. CRAIG Dec. 22, 1953 METHOD AND APPARATUS FOR HANDLING FERMENTATION GAS 5 Sheets-Sheet 3 [SNN NwNNS Filed July 19, 195i Y INVENTOR.

Patented Dec. 22, 1953 FFICE temann Company, Incorporated, Buffalo,v

Apiilti'niijie, 1951; seria-1 nl esmas i l'ais. (ci. 6241)" This invention relates to apparatus by means of Whichfermentation gases as they are` received from a fermenter are compressed and' stored for use in vapor andliquid-phases. Y

In places, suchfor example as'breweries, where fermentation gases are evolved; and usedin con# nection with the handling of the product, the quantity of fermentationA gas; produced may' vary greatly from day to day, and also the'consump'- tion of ,such gasesforvarious purposes may' vary, so that at times when large quantities of gas-are produced, only small quantities 'may be" used',y 'and vice versa.` It is, therefore, necessary to provide means for the 'storing-of g-as in relativelytlarge quantities atv times; and heretofore vthis fermens tation gas has been storedin liquid form'in-Wliich it occupies veryfvmuclr less` s'paceithanf in' the gaseous form. Thisliqueed gas'was then`va` porized as required'.

Oneof the objects offthisinventior'is .toproe vide an efficient.` andeconomical method and apparatus Vfor holding fermentation gas 'in such' amanner that a-conStant'supply of gas in vapor form is available at al1 times. l t

Another object -istoprovidea method vand 'ap`' paratus by means of 'which onlyvsuch` gas as is not required for use infvapor form isliqueed.

A further object vis to providexapparatus of this type which is entirely automatic in'operat'ion'.N

A urtherobjectfis to provide apparatus by means of which liquefied fermentation'gas' is vaporized automatically land supplied toa vapor storage tank AWhen-pressurev in th-elattr falls below apredeterminedminimum.v t Anotherobject is,v tosprovide apparatus vvherel by liquid fermentation-gas may be automatically vaporized and suppliedA to avapor storagetarik even lWhile the gas is-'being supplied thereto from a compressor, in the; event thatthepressurein the vapor storage tankibecomes low.' Y

A further obj ect is to provideapparat'usWhere;- by yif the pressure injA the liquid receiver becomes excessive, gas from; the-:head rspace' in* the i liquid receiver is recirculated throughv the"'apparat'us` and again liquened: L In Another "-Obict is t9AC Preti/de.; apparatus, by means" of vvhicht receiver is incr y f t falls be lovv a certain point-fbi: addigfadditional liquefied farmeriiiatiorfigas'thfetci. c

Another" object l'i ssurein the liquiasas.

, 2 s gas, the refrigerant compressor will operate in conjunction, with any of the fermentation gas compressors, l

`4-A further `object` is yto provide apparatus of this typeryvith improved means for evaporating liquid` fermentationgas.

Other objects; and advantages will be apparent from: the following, `description of vone embodif ment of the invention andI the novel features will be particularly pointed out hereinafter in connection with the appended claims.

Inthe accompanying drawings: s v

Fis-L 1 is ardiasrammeticlview of a part Oia fermentation `gashandling apparatus embodyinglthisinvention- Fig. 2 isa diagrammatic view ofV the remainingpart of the apparatus.v l

Fig- 43H is a diagrammatic view showing the electrical connections between the various parts of the apparatus.` I Y y l In the particular embodiment of the invention illustrated by Way of example in the drawings, I have shown diagrammatically in Fig. 1 one of a series of fermentationvats 5 in which the fermentation gas is evolvedl and which is connected by means cfa conduit 6 including a check valve 1 with areceiver il' invvhich the fermentation gas from ,thevat o r vats is collected at 10W pres-V sure, slightly above that of the atmosphere. v9 represents a compressorfor the fermentation gas and which is connected With the receiver 3 by means of an inlet p ipe l0. Vy'hileonl'yY one compressor is shownl in Fig. 1, it Will be understood that any desired number of compressors may be employed, dependingjapon the quantity of fer-y mentation gas to be handled. Thesecompressos may` be of an'ysuitable kind and are preferablyA of a type heretoforeused uin breweries' for com pressing carbon dioxideferrnentation gas without excessive rise in temperature during vcompression. v i

The compressed gas is discharged from the com-4 pressor or compressrsintofa receiver or surge tanlgjl through ,a-suitablepipe or conduit .i2.

' In this receiver some-of' the "entraiiied, free ".lrroisl-v tu e in the fermentation/gas is collected and some ofthe WatervaIiO'r is condensed and re-I tained for` periodic removal; Since theA compressed fermentation gas' Vcontains a certain amount of water vaporwhich is not condensed in the surge tank Il andfwhichvvold interfere with the liquefying Vand storageof the fer--I mentation 1 gas, the compressed gas fromthe surge tank Il is by means oflaconduitj through suitable means for removing vva'ter vapor aocaisd.

therefrom, and by way of example, I have shown a pair of drier towers I5 suitably connected with the conduit I4 so that the compressed fermentation gas may be supplied to either of the drier towers. The drying towers may be of any usual construction, and are, therefore, not described in detail. The drying medium contained in these towers may be of the desiccant type and must be treated from time to time to remove water therefrom. This is preferably done manually at intervals and the valves shown are operated manually so that when material in one tower is being dried, the other tower may be kept in operation. The compressed fermentation gas is discharged from the driers at a Very low moisture content through a pipe I6 which may, if desired, lead to another pair of towers I8 containing material for deodorizing the fermentation gas. The discharge of gas from the pipe I5 to eitherone of these towers may be effected by means of manually operated valves at the inlet and discharge ends of the tanks for the same reason specified in connection with the drier tower I5, so that the material in one tower may be re-activated while the other tower is in use. The deodorized gas from either of these towers passes into a pipe I9. The deodorizing towers may contain activated carbon or other material capable of removing odors from the gas and this material may be re-activated as is well known in the art.

The compressed gas in the pipe I9 is now ready for use in a brewery or other establishment in which the apparatus is installed and may be delivered :from this pipe Veither to a series of vapor storage tanks or it may be liquefied and collected in a liquid storage tank 2|, Fig. 2.

My improved apparatus is designed primarily to maintain a constant supply of fermentation gas in vapor phase to the vapor storage tanks 2t within a predetermined range of pressures so as to be available for use at all times. If the pressure in the vapor storage tanks reaches the low point of a predetermined range, then fermentation gas from the pipe I9 is supplied directly to the vapor storage tanks. When sufficient fermentation gas has been supplied to the vapor storage tanks so that the pressure of gas therein reaches the upper limit of the predetermined pressure range, then additional gas from the pipe I9 is conducted to the liquefaction cycle and discharged in liquid form into the liquid storage container ZI. If at any time the quantity of gas withdrawn from the vapor storage tanks exceeds the amount of gas which can be supplied to these tanks from the pipe I0, then fermentation gas in liquid form is evaporated into the vapor phase and supplied to the vapor storage tanks 20 to maintain a constant supply and pressure in these tanks, so that at any time when gas is required for use, a dependable and adequate supply is available. By means of the apparatus shown, all of this is accomplished automatically. The apparatus is also so constructed that all available gas from the fermenters is collected and stored either in the vapor or liquid phase within the range of the compressor capacities. Consequently, waste of fermentation gas is avoided and the collection of the same is not dependent upon the human element.

The storage of fermentation gas in the apparatus shown, consequently, falls within four basic cycles:

1. The collection and storage of fermentation gas in the vapor storage tanks.

2. The liquefaction of excess fermentation gas collected and compressed by the compressor or compressors 3.

3. The evaporation of liquid fermentation gas and return of the same to the vapor storage tanks.

4. The blow-off or relief of pressure in the liquid storage tank, if it exceeds a maximum predetermined pressure.

These four phases are all interconnected and operate according to the basic requirements im-i posed upon the system and are controlled from a central point.

Collection of gas in vapor storage Referring again to Fig. 1, 2B represents a valve which is opened when the pressure in the vapor storage tank reaches a low point in its range of pressures. This valve is located in a pipe which is connected with the pipe I9 and the valve is connected with another pipe 26 leading to the Vapor storage tanks. The discharge of fermentation gas in vapor phase for use in the brewery or other establishment may be through a pipe 2T.

A number of valves used in this system may be controlled by an actuating fluid under pressure such, for example, as compressed air. However, since carbon dioxide or fermentation gas is available under pressure, this gas is used in the particular apparatus illustrated for actuating the various Valves.

In Fig. l, I have shown a pipe 30 for such actuating iiuid which may, for example, be connected with the pipe I2 leading from the compressor 9. The pipe 30 leads to a reducing valve 3| which reduces the pressure of the actuating gas to that desired, and this lower pressure control or actuating gas passes from the reducing valve through a pipe 32 to a three-way valve 33 which is actuated by a solenoid 34, the electrical connections to which will be hereinafter described. By means of these connections the solenoid 33 becomes energized to open the valve 33 when the pressure in the vapor storage tanks 20 rises to the upper limit of the range of pressures to be maintained in the vapor storage. This three-way valve 33, when moved by the solenoid 34 into open position, admits actuating gas to a pipe 35, and when in closed position discharges the gas from the pipe 35 to the atmosphere. The pipe 35 is connected by means of a branch pipe 3B to a diaphragm 3l which controls the normally open valve 23 to close the same when no pressure acts on the diaphragm 31 thereof. Consequently, when the solenoid 34 is not energized, fermentation gas from the pipe I9 will pass through the pipe 25 to the vapor storage tank or tanks 20, or directly to the pipe 21 for use in the brewery. The pipe 35 also connects with a diaphragm 38 of a valve 39 which is normally closed and is opened when pressure acts on the diaphragm 38.

When sufficient fermentation gas has been supplied to the vapor storage tanks 20 to raise the pressure in the saine to a predetermined point the solenoid 3:1 is energized to move the valve 33 into a position in which control or actuating gas is supplied to the pipe 35. Consequently, Awhen pressure acts on the diaphragm 38, the valve 39 is opened to permit fermentation gas to pass through the pipe 40 to the liquefaction cycle which is shown in Fig. 2, and at the same time, this pressure closes the normally open Valve 24. There is also shown in Figs. l and 2 a pipe 4I through which fermentation gas may pass to the pipe 25 and to the vapor storage tanks 2U after liquefied fermentation gas has been again vvola- 5. tilized in response to a demand for fermentation gas in the vapor storage tanks ..20 `above that which can be supplied directly without being liquefied, and through which. `fermentation gas may pass to the vapor storage in case the pressure in the liquid storage becomes excessive.

Liquefaction cycle Fermentation gas to be liquefied passes through the pipe ill past the diaphragm-controlled valve 44, a hand-operated valve 45, and a checkv valve 46 to a condenser 41.' This condenser may be of any suitable or desired type, that shown diagrammatically being of a double pipe, U-tube form, and any desired number of these tubes may be employed. In the construction illustrated, the inner tube of the condenser receives refrigerant and the fermentation gas to be liquefied passes through the space between the two tubes of the condenser and is discharged in liquid form through a pipe d8 and through a hand valve 49 to the liquid storage tank 2|.

The refrigerant employed may be of any suitable kind, ammonia being'preferred, which may be compressed by means of an ammonia compresser 56 of any suitable type, which may, for example, be driven by an electric motor 5 I.

lvy improved apparatus may be operated at any desired pressures, this being particularly the case with reference to the vapor storage tanks 20, which may be operated at any pressure desired in the brewery in which the apparatus is installed. lf, for example, the pressure desired in the vapor storage tanks is approximately between 160 and i8() pounds per square inch, then if the pressure in the vapor storage tanks drops to about 160 pounds per square'inch, fermentation gas will be' supplied thereto. If the pressure in the vapor storage tanks reaches approximately 180 pounds per square inch, then the solenoid 34 will actuate the valves 33, 24 and 39 to transmit additional fermentation gas to the condenser or condensers 4l. The fermentation gas compressor 9 is capable of delivering fermentation gas at pressures materially in excess of those required for supplying gas to the vapor storage tanks 20, and in the apparatus described the fermentation gas is preferably liqueed at a pressure of about 250 pounds per square inch. Consequently, by the use of Iny improved apparatus, any fermentation gas compressor used is capable of delivering fermentation gas either at the'pressure required in the vapor storage tanks 20 or for delivering fermentation gas at a higher pressure for liquefaction. If more than one compressor is used, such compressors are Iconnected in parallel relation to each other for taking care of larger capacities, but in my apparatus as shown, no additional compressors are required for boosting the fermentation gas from the vapor storage pressure t0 a higher pressure for liquefaction.

Assuming that the pressure in the vapor storage tanks has increased to the upper limit of the range of pressures, for example, 180`pounds per square inch, and the compressor or compressors 9 and the refrigerant compressor 5I] are operating, a three-way valve 55 will be actuated by means of a solenoid 56, as'will be hereinafter explained. This'v'alve is arranged in a conduit 51 connected with a conduit 58 leading from a pressure reducing valve 59 which receives gas through a conduit 60 connected with the pipe 4| which, in turn, is connected through pipe 26 with the vapor storage tanks 20. This reduced 'controlor actuating gas passingtothe pipe 51 is discharged "ac-segr 521 by means. or the valve 5ei11ntdaic-onduitz' con@ nected with a 'diaphragm '6.3 aoff the valve .4.4. and with anotherdiaphragm .6,4 'connected'with a valve B5 in the refrigerant line'so. that both valves 44 and 65 will be opened simultaneously to admit fermentation gas 'and refrigerant to the 'condenser 41. For the sake of clarity, the entire refrigerating cycle, including the ammoniav corn'- pressor 50, isnotjher'ein shown .in detail, since, it may be of any usual or suitable type. Liquid ammonia or other refrigerant from this system passes to the valve 65. through a conduit '6.1 and flows to an expansion valve. 68. This 'valve' is thermally operated in any usual'or lsuitable manner, as by means of a thermostat or temperature responsive device 69, which is responsive; to the temperature in the refrigerantdischargeV pipe' T0 leading from'the condenser 41' to'the 'intake of the refrigerant compressor 50. means of this arrangement, the liquefyingofthel'ermentation gas Iwill be automatically controlled by the temperature of the refrigerant rdischargedfrom the condenser, and since the pressure in the liquid storage tank 2l Will be maintained at. approximately 250 pounds, the pressure of the. fermentation gas will be automaticallyincreased by the compressor so thatit may passthroughthe check valve 46 and the condenser 4'1;v

If, at any time the use. of'y 'compressed .gas from the vapor storage tanks' Zuexceedsfthat whicliis supplied to these tanks by theA compressor` eso that the pressurel inthe 'vapor storage tanks 2.0 falls below the desre'dminimum, for example, 160 pounds per square inch; Aetwa-'way valve '1'4 controlled by a solenoid 15 willbe 'olvn'enedg` This valve is connected iwiththei conduit 58 carrying control or vactuating gas.: 'valve '1.4. admits control gas through a pipe'ltda 'valve `1T actu.- ated by means of a 'solenoid J8 to" the. diaphragm .19 of a valve 80, when the. valve llsrdpemf This valve controls the fiow of' liquid fermentation gas passing through a pipe. al and pasta handoperated valve 82 tn ajlevl switch 8'! and then through conduit. 585 to' an evaporator 8.' The level control valve. 84 maybe of. anysuitable or usual construction, and` since valvesof thiskind may be purchased in the. open market, no detailed description is deemed necessary. This. valve is connected by means/off 'ano'tlle'rV pipe 8J 'tothe upper portion of the evapxzaratory 83T.l Ther liquid fermentation gas. will'floiu through lthe; pipe 85 into the evaporator until it reaches a maximum level, whereupon, theY level*'controlswitchl 84 will stop further flow of liduid fermentation gas into the evaporator until the level inthe evaporator becomes lower.. due to.. evaporation ofv the-liquid gas therein. The level switch 84acts.` through. the solenoid 18 and the valve. H to'close'theval-ve 80 whenthe desired liquidflevel `in the evaporator has been reached,J as will be hereinafter explained.

The yevaporator 86 for changing thdphase of the fermentation gas from :liquid to vapor-isgbreferably in thev form of an inverted U-shaped heat exchanger mounted 'in a. ver-tical position with the U bend at the uppermost pQnt.-.The-evap orator has an inner tiubefthrough which. theheating medium ows. The liquidifermentation-gas is admitted into thespace betweentheinnen and outer tubes of the evaporator.

Any suitable heatingmedim maybe empldyed for vaporizing the liquidfermentation-sanctie in the construction shown, steam or hot vapor is employed as the lheating medium in the evaporator. The `steam or other'heating medium may be admitted from a suitable source to a tube 90 and if the steam is of relatively high pressure, it is passed rst through a reducing valve 9 However, a valve controlled by-pass 92 is provided through which the heating medium may be passed if a reduction valve is not necessary. A drip trap 93 may be provided for receiving condensed steam. The ow of heating medium to the evaporator through pipe 90 is controlled by means of a valve 94 operated by a diaphragm 95 and the pipe 90 terminates in one end of the inner tube of the evaporator. The other end of the inner tube is connected by means of a pipe 95 to a steam condensate tank 91 provided with -:an outlet 98 for the condensate.

The condensate tank 91 contains a heat responsive device such, for example, as a thermo- ,stat which controls the extent to which the steam :admission valve 94 is opened to admit the heat- .ing medium to the evaporator, in such a manner that if the condensate is of less than a desired temperature, the valve 95 will be opened to a greater extent and if the temperature of the condensate is too high, the valve 95 will move toward closing position to restrict the amount of heating medium supplied to the evaporator. This thermostatic control serves to economize the use of steam or other heating medium and also to prevent the condensate from freezing in the evaporator. The valve 14 admits control gas to a thermostatically controlled valve (not shown) in the condensate tank 91, by means of a pipe |00.

|| represents a discharge pipe for the control of actuating gas from the thermostatically controlled valve in the steam condensate tank 9?, this pipe leadingto the diaphragm of the valve 494. The thermostatic device within the steam condensate tank varies the amount of control gas which flows through the pipe |0| in such a manner as to regulate the amount of steam passing to the evaporator in accordance with the ternperature of the condensate discharged from the evaporator.

The vaporized fermentation gas leaves the evaporator through a pipe |02 and passes through a check valve |03 to a heater |04 which is in the nature of a small heat exchanger which may, for example, contain an electrical resistance heating unit (not shown) for raising the temperature of the vapor, if necessary, to prevent frosting Ion the pipes conducting the vapor to the vapor storage tanks 20. This electric heating element is preferably connected in the circuit at the same time that the valve I I8 is opened. By heating `the gas, frosting of the exterior of the pipes |05 and |01, and consequently, dripping of moisture therefrom is avoided. After passing through the heater |04, the vapor passes through the pipe '|05 to a pressure reducing valve |00 and then through pipes or conduits |01 to the pipe 4| leading to the vapor storage tanks. If desired, a now meter |08 may be included in the pipe |01 to indicate the rate of ow of gas from the evaporator to the liquid storage tanks 20, but a valve controlled by-pass |09 is provided in case the iioW meter is not to be used.

When the pressure in the vapor storage tanks "20 has increased to the desired extent, for example, to 170 pounds per square inch, the solenoid 15 of the valve 14 will be cie-energized, thus vclosing this valve as well as the valve 94 for the heating medium so that evaporation of liquid -fermentation gas is stopped.

If at any time the pressure of fermentation gas in the liquid storage receiver 2| should increase beyond that desired, for example, 260 pounds per square inch, a three-way valve ||5 controlled by a solenoid ||6 will be actuated to direct control gas, which may be received from the pipe 51, to a pipe ||1 to a diaphragm-actuated valve H8. The valve ||8 is in a pipe ||9 connected with the head space in the liquid storage receiver, and this pipe connects with pipe |02 leading to the heat exchanger |04. The heating medium in the heater |04 is preferably an electrical resistance thermostatically controlled device so that the vapor Will be warmed to the desired extent before passing through the pipes |05 and |01 to the pipe 4|. The gas thus discharged from the head of the liquid storage container, after passing through the heater, passes to the valve |00 and through or around the flow meter |08 and through the pipe 4| to the vapor storage tanks.

If the flow of fermentation gas from the liquid storage tank 2| continues sufciently long, the pressure in the vapor storage tanks 20 can increase until it reaches a point several pounds in excess of the maximum pressure which is normally maintained in the vapor storage tanks. When this occurs, a solenoid-operated valve |25, Fig. l, is opened by means of its solenoid |26, the circuit through which is closed by means of a pressure controlled switch on the vapor storage tanks set to operate at a pressure in excess of the normal upper limit of pressure desired in the vapor storage tanks. For example, if the range of pressure desired in the vapor storage tanks is to 180 pounds per square inch, this pressure controlled switch may be set, for example, at 182 pounds per square inch.

The valve |25 controls a valve |21 in a pipe |28 which connects with the pipe 20 leading to the vapor storage tanks 20. Control or actuating gas for the valve |25 may be taken from the pipe |28 and passed through a reducing valve |30 to a pipe |3| leading from the valve |25. When this valve is opened, control or actuating gas passes through the pipe |33 to the diaphragm |30 of Valve |21, thus opening this valve and permitting gas to flow through the pipe |28 to the pressure-reducing valve |3401, and then through a pipe |35 to the receiver 8. If the compressor 9 is already in operation, the valve 33 will, of course, have been actuated because of the high pressure in the vapor storage tanks to open the valve 3S to pass the compressed gas to the liquefaction apparatus. If the compressor is not op erating at the time gas is discharged from pipe |35 into the receiver 8, then increase in pressure in the receiver 8 Will start the operation of the compressor 9, as will be hereinafter explained. By means of this arrangement, vapor which might ordinarily be vented to the atmosphere from the liquid receiver through a safety valve, S either Put directly to use in the brewery or is put back into the liquid receiver in liquid phase,

thereby reducing the pressure therein.

Low pressure make-up in liquid receiver If at any time the pressure in the liquid receiver 2| falls, for example, to approximately 225 pounds per square inch, the liquefying cycle will become operative as previously described, and all vapor from the compressors will be passed through the condenser 41 into the liquid receiver. However, if at any time the pressure in the vapor weer storage tanks 2|) should fall tothe minimum of the range of pressure for the vapor storage tanks, the evaporation of liquid fermentation gas-would become operative and at the same time the liquefaction cycle initiated by the reduction in pressure at the liquid receiver and the evaporation of liquid fermentation gas would continue until the pressure in the vapor storage tanks 2|) has been restored, whereupon the liquefaction operation will again start'when the liquefyi-ng cycle has been initiated by reduction in pressure at the liquid storage tank 2|, liquefaction will continue until the pressure inthe liquid storage tank has been increased to approximately -250 pounds per .Square inch.

Electrical connections Electric power Vfor operating the Vsystem may be received from any suitable source, such as a transformer |45, the secondary terminals of which are connected to two main power lines |46 and |41 which supply the control system, Fig. 3.

The electrical connections shown includeka number of pressure controlled switches which are opened and closed by pressure responsive devices in various parts of the apparatus. Since pressure responsive devices which open and close electric circuits in accordance with pressures to Which they areeXposed are well known and are readily available Vfor purchase, it is not deemed necessary herein to illustrate such pressure responsive devices.

Liquefaction cycle |59 represents a pressure actuated switch which is responsive to pressures in the vapor storage tanks 25|, the switch being closed when the preissure reaches the maximum of its range and opened when the pressure reaches a desired minin mum. For example, the switch |50 may close at 180 pounds per square inch and open at 170 pounds per square inch. When the switch |50 is closed, current will pass through a coil |5| of arelay which has two sets of movable circuit closing contacts |52 and |53. The movable contact |52 completes a circuit through the coil e6 which actuates the control valve 55 whic-h admits control gas to diaphragm S3 to 'valve 44 for conducting fermentation gas to the condenser 41, and to diaphragm 64 ofv the valve t5 which admits refrigerant to this condenser. The circuit closing contact |52 also permits electric current to flow to thesolenoid coil 313' which actuates the control valve`33 to shutl oir the supply of fermentation gas tothe vapor storage tanks 25 and admit fermentation gas to the condenser Il?. lighted when the movable contact member |52 is in circuit closing position to indicate that the apparatus is operating on the liquefaction cycle. The movable circuit closing contact |53 closes a circuit through a conductor |55 to a solenoid |55 tor operating a starter for vthe motor (not show-n) which operates the refrigerant vcompressor or booster 5t. n v

Current is conducted to thestationary contacts 'with which the movable contact members |52 and |53 engage by means of a conductor |51 which is connected with the power line |454 by means of a movable contact member |58which is actuated by a solenoid |59 which is energized only when the Vmotor which drives the fermentation gas compressor is in operation. 'In other Words, the solenoid 155e moves the contact member |53 into circuit closing positioncnly when the compressor 9:. for theA .fermentation gas is operation', so

Ii desired, a pilot light |54 may also be that the liquefaction `cycle. cannot be operated 'except whenv this compressor` is operating.

, The operation of the compressor or compressors 9 is dependentupon the closing of another pressure switch responsive to the pressure in the receiver 8 in which the fermentation gasis collected before it passes to the compressor 9. I have illustrated diagrammatically by way of example in Fig. 3, starting mechanisms for three different compressors forthe fermentation gas. Any number oi these `compressors may, of course, 'be provided, and they may be Yoperated in accordance with the amount of fermentation gas delivered to the receiver 8. For example, if three different compressors. are provided, one of these compressors may be automatically started by a pressure switch when there is a pressure. of two pounds per square inch in the receiver 8. If the pressure in the receiver 8 reaches three pounds, the second compressor is started and if the pressure in the receiver continues to rise to four pounds, the third compressor will be started by means of another pressure rresponsive switch. In the construction shown, |60, |E| and |62 representy respectivelythree switches responsive to `pressures in the receiver 8. Since these three switches are all similarly connected, only one .of them will be described, but ther same reference characters apply to the various connections for the other switches.

When one of the pressure responsive motor starting switches |60, 16| or |62 is closed, a circuit is completed from the power supply line |46 to a solenoid |65 which actuates a motor starter |66 for starting a motor (not shown) which operates a fermentation gas compressor 9. The pressure-responsive motor starting switch also closesA a circuit through an auxiliary contact |61 leading to a solenoidv |68 which, when energized, moves a movable contact member |69 into engagement with the adjacent terminals. One of these terminals is connected by means of a conductor |10 vto the power supply line |41 and the other terminal connectsA with a conductor |1| which leads `to ther solenoid' |59 and energizes the same 4to move the movable contact member |53 into switch-closing position vso that current may be supplied tothe solenoids 56 and 34 and to the solenoid Y|55 which is connected with the starter for the refrigerant compressor, when the switch |50 is closed. It will thusbe seen that if the starting vswitches for one or more of the motors operating the fermentation gas compressor or compressors isnot closed, then there also will be no current flowing through solenoid |59 so that the ammonial compressorwill not. be operated and no gas. will be conducted to the condenser 41.

If, at any time, there .should appear in the ammonia. compressor `starter an increase in current, which might be due toen overload ofthe motor driving this compressor, means are pro? vided for stopping the operation of the fermentation gas v compressors and for preventing the actuation -of valves forl passing' fermentation gas vapor to the condenser 41. Inthe particular construction shown forv this purpose, a' heater coil circuit |15 of any usual or suitable type is included in the starter ofthe motor driving the ammonia compressor. The coil |68 is connected by means ofv a conductor |16 through the heater coil circuit |15 to the power supplyv line |41, and consequently, if this heater circuit is broken, due to excessive currentsupplied vto` the refrigerant 11 compressor motor, the circuit through the solenoid coil |68 will be broken, thus interrupting the supply of current through conductor |1| to the solenoid coil |59. When this circuit is broken, the supply of current to the solenoids 55 and 34 and to solenoid |55, which starts the ammonia compressor motor, is broken, thus stopping this motor and preventing actuation of valves of the liquefaction system.

Similarly a heater coil circuit |18 is provided in the circuit leading from the solenoid |65 to the conductor |16. Consequently, if only one fermentation gas compressor is operating and the circuit through the heater coil |18 is broken, then the motor driving the fermentation gas compressor will be stopped, since no current will flow through this solenoid coil |65. The heater coil |18 is operatively connected with the auxiliary contact- |51, thus moving this contact into open circuit position to interrupt the flow of current to the coil |68. This results in moving the circuit closing member |69 into open circuit position and thus interrupting the flow of current to the solenoid |59, so that no current is supplied to the compressor motor starter nor to the solenoid coils 56 and 34, this making it impossible to operate the liquefaction cycle. If the overheating of either the heater coil |15 for the refrigerant compressor motor or the heater coil |18 of the motor which drives the fermentation gas compressor results while the liquefaction cycle is in operation, then this cycle will be terminated at once, due to interruption of current supply to the solenoid coil |59. By means of this arrangement of parts, the apparatus is adequately protected in the event of motor failure at either the refrigerant gas compressor or the fermentation gas compressor. If more than one fermentation gas compressor is employed, the rise in pressure in the receiver 8 due to stopping of one compressor will cause the next fermentation gas compressor to begin operation so that the apparatus will continue to operate However, if more than one fermentation gas compressor is operating, when one of the heater coils |18 operates to move its contact member |61 into open circuit position, the other fermentation gas compressors will continue to operate, and also if the switch |50 which places the liquefying cycle into operation is closed, the refrigerant compressor will continue to operate. However, if the heater coil |15 of the refrigerant compressor opens the circuit |16, then the liquefaction cycle will be stopped through coil i 59. The fermentation gas compressors may, however, continue to operate to supply fermentation gas to the vapor storage tank or tanks 20.

In the normal operation of the apparatus, the liquefaction cycle, after it has been started, will continue to operate until the pressure in the vapor storage tanks 20 drops to the lower limit of the pressure range for the vapor storage tanks 20, for example, 170 pounds per square inch, at which time the pressure controlled switch will open. When this occurs the supply of electric current to the solenoids 56 and 34 will be interrupted, whereupon the flow of control or actuating gas to the diaphragms 31 and 38 will be interrupted by the valve 33, Fig. 1. Since the valve 39 is direct-acting, it will close when the supply of pressure to the diaphragm 38 is interrupted, and the valve 24 will be opened when the supply of control gas under pressure to its diaphragm 31 is interrupted. The fermentation gas from the pipe I9 will, consequently, be admitted to the vapor storage tanks 20.

, 12Y Evaporation cycle The control of the evaporation cycle of the apparatus may be effected as follows:

If the pressure in the vapor storage tanks 20 drops to the lowest level of the range of pressures at which gas is to be maintained in these tanks, for example, 160 pounds per square inch, then a pressure-responsive switch |80 will be closed to complete a circuit from the power supply line |56 to a conductor |8|, which connects with a solenoid |82 by means of which a movable contact member or switch |83 which is normally in closed position, is moved into circuit-opening position for the purpose hereinafter described. When the switch |80 is closed, current will also low to a solenoid |85 of a two-pole relay, including circuit closing members or switches |86 and |81. The circuit closing member |85 is normally closed when the relay |85 is not energized and this circuit closing member completes a circuit through the pressure responsive switch |50 and a conductor |89 leading through a manually adjusted selector switch |90 to the power supply line |51. The selector switch |90 is manually operated and when the movable switch member engages the contact |9I, the liquefaction system will be operated automatically. If it is desired to operate this system manually the movable switch inember |90 is moved into engagement with a contact |92. When the movable switch member 98 is in an intermediate position between the contacts |9| and |92, as shown in Fig. 3, the liquefaction system will not be operable. The movable switch member will, during normal or automatic operation of the apparatus, be left in position to contact with terminal |9|. When the pressure switch |80 is actuated because of an excessive drop in pressure in the vapor storage tanks, the switch |50 should be open, since, as described, it opens at a higher pressure than that required to actuate switch |80. By means of the contact member |86, the ow of current through the solenoid coil |5| is interrupted, even in the event that the switch |50 should fail to function, so that the liquefaction cycle will be positively shut down, thus ensuring that the fermentation gas from the compressor will go to the vapor storage tanks.

The circuit closing member |81 is normally in open position, but is closed when the solenoid |85 is energized. When the contact closing memg ber |85 is closed, current will now from the conductor |8| and through solenoid coil |82 through the switch member |86 to a conductor |93 which leads to another manually operable selector switch |94 similar to the selector switch |90, to the supply line |41.

A branch conductor |95 connects with the conductor |93 and supplies current to the solenoid 18 of the valve 11 which supplies control gas to the diaphragm 19 of the valve 80, thus admitting liquefied gas from the liquid storage tank 2| to the evaporator 86. The conductor |93 also connects with a branch conductor |91 leading to the solenoid 15 which when energized opens valve 11i which admits lcontrol gas to the valve 11 for actuating the diaphragm 19 of valve 80. The valve 18 also allows control gas to pass to the control system for the flow of heating medium, such as steam, to the evaporator. Evaporation of the liqueed gas will, consequently, be effected and this evaporation will continue until the vapor storage pressure in the tanks 20 rises to the pressure intermediate of the range of pressures designed to exist in the vapor storage tanks, such assess for exanuzvle as a pressure of. 170.. pounds per squareinch. When this pressure is reached, the pressure control switch |80 .will open, thus interrupting the liquefaction cycle, .and this, .again will cause the circuit closing member |56 to move linto circuiti-closing position to enable the pressure controlled switch |59 to become .operative when the vapor storage reaches` a pressure Yat the upper limit of its range, for example, 180 pounds per square inch.

When the manually movable switch member |94 is moved into engagement with the contact |98, the liquefaction system will be operated automatically. If it is desired to. control this system manually, the movable switch member |94 is moved into engagement withV the contact |99. If the switch member .|94 is i-n aposition intermediate between the two. terminals 99 and |99, the liquefaction system will. be'inoperative. When the switch member |86 is in its circuit closing position, current will be conducted from the conductor |93 to a conductor |84 through a heating cable, |88 which is arranged in operative relation to the valve 80 to prevent the formation of frost about this valve .in such a manner as to render it inoperative. Any other means for preventing frosting of this valve may, of course, be provided. |96y represents a signal light which is illuminated to indicate that the evaporation cycle is in progress. Y Pressure relief cycle If at any time the pressure in the liquid storage tank 2| increases to a pressure in excess of that at which it is intended to operate, for example, if this pressure increases to 260 pounds per square inch, it becomes necessary to relieve this pressure. When this is done by the ordinary safety or blow oil' valve, the excessr fermentation gas is lost or wasted, and in order to avoid this waste, I have provided in the apparatus means for supplying this gas to the vapor storage tank 2li for immediatev use; or, ifv this raises the pressure excessively inthe vaporstorage,` then to liquefy the excess gas and return it to the liquid storage container 2|.

The means for accomplishing this result are constructed as follows:

200 represents a pressure controlled switch which is responsive to pressures in the liquidstorage tank 2| and which is closed when the pressure in the, liquid storage tank reaches the maximum. This switch connects with a conductor 293i leading; to' a manually operable three-way selector switch 2,02. When the movable switch member is in engagement with the stationaryfcontact 233,- the pressure relief cycle will he operated automatically. When this manually controlled switch 202 engages the Contact 204, the pressure relief mechanism will be operated manually; yand 'if theV movable switch member is in'an intermediate position between these two contacts, the pressure relief mechanism willbe inoperative. y

Assuming `that the rswitch member 252- engages contact, 203', a. circuit willbe closed-including a conductor. 2.05 from which a branch conductor leads to a solenoid 201 oa relay havingr two movable circuit closing members. 2li! land 21|'. When the solenoid 201 `is energized, the movable contact member 2li will complete a circuit to a conductor 2|2, through a thermostetically con.;` trolled contact switch 2,|4. -The thermostat. or other temperature responsive device which confr trols the-switch 2-|4 should be so jlocateol as to be acted upon by the Afermentation gas leaving the heater: |04; soV thatlthe switch 2f|4`will be closed when temperature. of this-.gas leaying theheater below that desired, and the switch will be closed and when thisv temperature, .is ink .excess of .that desired, the swtcjhi will be opened. If 'the gas temperature decreases sufficiently to close.v the thermostatic switch 2 I4, then a relay 2 I5 will vbe energized lwhich also hasl two circuit closing devices 2|6 and 2H, thus closing a circuit to an electric heating unit 2|8 arranged in the heater |04. Since the circuit through the gas heater is at higher voltage than the control circuit, the heat circuit is not completely shown, it being understood, however, that this vcircuit is connected to the terminals 220 and 22|, which when contacted by the movable contact members 2| 6 and 2H will supply current to the heaterin accordance with the' action vor" the thermostatically controlled switch 214.

When the solenoid 297 is energized and the movable. contact member 2|!! is in circuit closing position, currentwillbe supplied to a conductor 223 leading to a pilot light 224 which indicates when the pressure relief cycle is in operation, and toasolenoid H6 which controls the three-way valve I|5 for admitting control or actuating gas through pipe l1 to the diaphragm of valve IIB, which is opened when control gas acts on the diaphragm of this valve. A heating element 245 warming the valve ||8 also is energized when contact member 2 I0 isin circuit closing position. When this valve is open, gas from the head of the liquid storage tank 2| will be passed through the heater |04 and reducing valve |06 back to the vapor storage tanks 29. This results in reducing the pressure within the liquid storage receiver 2|. When the pressure relief cycle is in operation, the pressure in the vapor storage tanks 20 may increase to the upper limit of its range of pressures, thus causing the liquefaction cycle to become actuated through the pressure switch |50. However, because of the connections described, the liquefaction cycle cannot become operative unless the fermentation gas compressor is operating. If thev pressure in the receiver 8 is too low to cause the` compressor 9 to operate, then the liquefaction cen, of course, not take place. To take care of this emergency another pressure controlled switch 23|) is provided which is responsive to pressure in the vapor storage tank 20 and which is closed when the pressure in these tanks rises slightly above the maximum of the pressure is obtained in the receiver t, the corn-v presser 9 will operate as heretofore described. Gas from the receiver S will then be compressed and pass to the liquefaction condenser. The liquefied fermentation gas .will pass into the liquid storage vcontainer 2| *and this operation will continue untilthe pressure in the liquid storage tank 2| is reduced to the. maximum pressure at'which it is intended to operate, .forexample 250 pounds per square inch. The liquefaction cycle will then Continue ,tof:operateulfltil the/pressure in the vapor storage tank 20 is reduced to the low. pres.- sure of its pressure range, forA example,

pounds per vsquare inch. "When lthe pressure the vapor storage tank 20 is reduced to a predetermined point, such, for example, as 172 pounds per square inch, the pressure switch 239 will be opened, thus stopping the pressure relief cycle.

Low liquid pressure make-up in liquid receiver into circuit closing position. This pressure controlled switch 235 is connected in the circuit in parallel with the vapor pressure controlled switch |50. If the pressure switch |50 is already closed, then the liquefaction cycle will be in operation.

The necessary step for increasing the pressure in the liquid receiver is in progress and the closin-g of the switch 235 will have no further eiect. If, however, the pressure switch |50 is open because of low pressure in the vapor storage, then the closing of the switch 235 will start the liquefaction cycle, unless the vapor storage pressure has previously been reduced to the low point of its range of pressure, for example, 160 pounds per square inch so that the pressure switch |80 is closed to cause the evaporation cycle to start.

In that event, the solenoid |82 would be ener- 'i gized, thus moving the movable contact member |83 upwardly to break the circuit through the pressure switch 235 and also in parallel with the switch |50, thus breaking the liquefaction circuit.

However, if there is no demand for evaporation and all of the gas from the fermentation gas compressors is passed through the liquefaction condenser into the liquid receiver 2| and will continue to do so until the pressure in the receiver 2| builds up to approximately 250 pounds per square inch. This phase of the operation is only interrupted if there is a demand from the vapor storage tanks 20 for evaporation of liquid fermentation gas if the pressure in the vapor storage tank falls below the low pressure in the range of pressures, for example, 160 pounds per square inch. At such times not only will the liquefaction phase be stopped, but gas from the fermentation gas compressors will pass directly to the vapor storage, since the valve 34 will be energized.

The apparatus described may be operated manually by means of the three manually operated selector switches |90, |94 and 202. For example,

if it is desired to condense all vapor collected from the fermenter, then it is only necessary to place the selector switch |90 into position for manual operation, namely, into engagement with the stationary contact |92 and the selector switch |94 into an intermediate position between the two contacts |98 and |99. Condensation of fermentation gas will then take place continuously until the switches are again returned to either their olf positions or their automatic positions.

If it is necessary to quickly obtain vapor inV 202 can be put into contact with the terminal Zilli whereupon the vapor in the head space of the liquid receiver 2| will be returned to the vapor storage tank 20. It may be desirable at times to operate this phase manually in order to quickly make up vapor requirements at the vapor storage receiver 29.

All phases of the system may be cut out by putting any one or all of the manually operable selector switches into the off position.

240 represents a hand-operated blow-oif valve which may be opened at intervals to permit any air to be discharged from the liquid storage tank 2|, and 24| represents a hand-operated valve through which liquid or sediment collected in the bottom of the storage tank 2| may be drained. A number of hand-operated valves in addi tion to those specifically referred to are shown in the drawings, and it will be obvious that these valves may be employed for the purpose of manually interrupting the flow of gases and liquids in certain parts of the apparatus for cleaning, maintenance or repair of such parts. Also check valves, in addition to those herein referred to, may be applied to the apparatus wherever necessary.

The liquid storage container 2| should be well heat insulated and kept in a cold room, as has heretofore been customary. By maintaining the vapor storage at a lower pressure than the liquid storage, there will be no difhculty in transferring vapor from liquid storage, either by the blow off or by evaporation, to the vapor storage.

It will be understood that various changes in i the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention, as eX- pressed in the appended Claims- I claim as my invention:

1. Apparatus for Vhandling fermentation gas including a compressor for compressing said gas, a storage tank for said gas in vapor phase, a condenser cooled by a refrigerant and in which said compressed gas is liquefied, a receiver for liquefied gas, a valve controlling the passage of compressed gas to said vapor storage tank, a second valve controlling the passage of compressed gas to said condenser, and a pressure responsive device responsive to pressures in said vapor storage tank which affects closing said second valve and opening said first valve when the pressure in said vapor storage tank is less than the maximum desired pressure and which aifects closing said Vfirst valve and opening said second valve when the pressure in said vapor storage tank is below said desired maximum, whereby only compressed gas in excess of that required in said vapor storage tank is liquefied.

2. Apparatus according to claim l, and including a heating device for vaporizing liquid fermentation gas, a conduit which conducts said vapor to said vapor storage tank, and a pressure responsive device responsive to pressure in said vapor storage tank when the same falls below the minimum pressure desired therein for actuating said vaporizing means.

3. Apparatus for handling fermentation gas including a compressor for compressing said gas, a storage tank for said gas in vapor phase, a condenser cooled by a refrigerant and in which said compressed gas is liquefied, a receiver for liquefied gas, a pressure actuated electric switch responsive to pressure in said vapor storage tank,

"I7 a solenoid actuated valve, electrical connections between said switch and solenoid for conducting electric current from said switch to the solenoid of said valve, andlfiow control devices actuated b'y said valve for supplying compressed vapor to said vapor storage tank when the pressure therein is below the desired maximum and for interrupting the supply of compressed gas to said vapor storage tank and directing gas to said condenser when the pressure in said vapor storage tank reaches the desired maximum, whereby a constant supply of compressed gas is maintained in said vapor storage tank.

4. Apparatus for handling fermentation gas including a compressorfor compressing said gas, a storage tank for said gas in. vapor phase, a

' condenser cooled by a refrigerant-and in which said compressed gas isliqueed, a receiver for liqueed gas, a .pressure actuated electric switch responsive to pressure in Asaid vapor storage tank, a solenoid actuated valve, electrical connections between said switch and solenoid for conducting electric current from said switch to thesolenoid of saidV valve, flow control devices actuated by said valve for supplying compressed vapor to said vapor storage tank when the pressure therein is below the desired maximum and for interrupting the supply of compressedv gas to said vapor storage tank and directing gas to said condenser when the pressure in said vapor storage tank reaches the desired maximum, whereby a constant supply of compressed gas is maintained in said vapor storage tank, mechanism for starting a refrigerant compressor to supply refrigerant to said condenser, and connections between said switch and said mechanism for actuating said mechanism. I

5. Apparatus for handling fermentation gas including a compressor for compressing said gas, a storage tank for said gas in vapor phase, a condensercooled by a refrigerant and in which said compressed gas is liqueed, a receiver for Vliquefied gas, a pressure actuated electric switch responsive to pressure in said vapor storage tank, a solenoid actuated valve, electrical connections between said switch and solenoid for conducting electric current from said switch to the solenoid of said valve, iiow control devices actuated by said valve for supplying compressed vapor to said vapor storage tank when the pressure therein is below the desired maximum and for interrupting the supply of compressed Vgas to said vapor storage rtank and directing gas to said condenser when the pressure in said vapor storage tank reaches the desired maximum, whereby a constant supply of compressed gas is maintained vin said Vapor storage tank, mechanism for starting a refrigerant compressor to supply refrigerant to said condenser, said mechanism including an electric circuit, and means for completing said circuit only when said first mentioned compressor is in operation.

6. Apparatus for handling fermentation gas including a receiver for said gas at low pressure, a compressor having its inlet connected with said receiver and for compressing the gas, a storage tank for compressed gas in vapor phase and normally connected with the discharge of said compressor, a condenser cooled by a refrigerant, a container for liqueed fermentation gas discharged from said condenser, a switch responsive to pressures in said low pressure receiver, a circuit closed by said switch for starting the operation of said refrigerant-gas compressor, a second switch responsive to pressure in said Vapor accenni storage tank. arelay moved into circuit closing A .circuit closing position, and control means actuated by said second circuit for passing compressed gas from said compressor to said condenser when pressure in said vapor storage tank reaches the desired maximum.

7. Apparatus according to claim 6, and including a third circuit closed when said second switch isA closed, and means actuated by said third circuit for admitting refrigerant to said condenser.

8. Apparatus according to claim 6 and including a third circuit closed when said second switch is closed, a refrigerant compressor for discharging refrigerant to said condenser, and means actuated by said third circuit for starting the operation of said compressor.

9. Apparatus according to claim 6 and-including a third circuit closed when said second switch is closed, a refrigerant compressor for discharg# ing refrigerant to said condenser, and driven by an electric motor, means actuated by said third circuit for starting said motor, and a device actua'ted when said motor is overloaded for moving said relay into circuit opening position to interrupt 'actuation of said control means and v to stop the passage of compressed gas to said condenser. A

l0. Apparatus for handling fermentation gas including a compressor for compressing said gas, a storage tank for compressed gas in vapor phase, a condenser cooled by a refrigerant, a container for liqueed fermentation gas discharged from said condenser, a pressure controlled switch responsive to pressures in said vapor storage tank and which is closed when pressure in said storage tank'is reduced to a predetermined point, an evaporator for liquened gas, means including valves and operating devices therefor operated by said switch for simultaneously admitting lique ed gas to said evaporator and applying heat thereto, said 'switch being opened for interrupting the supply of liquefied gas and the applica-'- tion of heat to Said evaporator when the pressure in said vapor storage tank rises to a predetermined point'.

l1. Apparatus according to claim l0, in which said evaporator is of'tubular form of inverted U-shape and in which liqueed fermentation gas is admitted to one leg thereof, and level control means controlling the supply of liqueed gas to said leg of said evaporator.

12. Apparatus according to claim l0, in which said evaporator is of double tube construction with one tube arranged within the other, the liquefied gas being admitted to one of said tubes and the heating medium in vapor form being admitted to the other tube, and means responsive to the temperature of the heating medium leaving the evaporator for controlling the admission of heated vapor to said evaporator.

13. Apparatus according to claim l0, in which said evaporator is of double tube construction with one tube arranged within the other, the liqueed gas being admitted to one of said tubes, means for supplying steam to the other of said tubes, and a valve controlling the admission of steam to said evaporator and responsive to the temperature of the condensate leaving the evaporator to admit more steam when the temperature of the condensate drops to a predetermined 19 point and to decrease the amount of steam when the temperature oi the condensate rises to a predetermined point.

14. Apparatus according to claim and in cluding a conduit for conducting vaporized refrigerant to said Vapor storage tank.

15. Apparatus for handling fermentation gas including a compressor for compressing said gas, a storage tank for compressed gas in vapor phase, a condenser cooled by a refrigerant, a container for liqueiied fermentation gas discharged from -said condenser, mechanism responsive to pressures in said vapor storage tank and including conduits and valves which direct compressed gas to said condenser when the pressure in said vapor storage tank exceeds that desired, an evaporator for liqueiied gas, and a low pressure responsive device connected with said vapor storage tank and which admits liquefied gas to said evaporator and which renders said mechanism inoperative.

16. Apparatus for handling fermentation gas including a receiver for said gas at low pressure, a compressor having its inlet connected with said receiver and for compressing the gas, a storage tank for compressed gas in vapor phase and normally connected with the discharge of said compressor, a condenser cooled by a refrigerant, a container for liquefied fermentation gas discharged from said condenser, mechanism respon sive to pressures in said vapor storage tank including valves, one of which is normally open when pressure in said storage tank is low to admit gas from said compressor to said vapor storage tank and which is closed by said mechanism when said pressure reaches the desired maximum, the other of said valves being normally closed and being opened by said mechanism when said nrst valve is closed, to admit compressed gas to said condenser for delivery in liquid phase to said liquid container, an evaporator for liquefied gas, and other mechanism responsive to a still lower pressure in said vapor storage tank and which renders said iirst mechanism inoperative and supplies liqueiied gas to said evaporator for transfer to said vapor storage tank.

17. Apparatus for handling fermentation gas including a receiver for said gas at low pressure, a compressor having its inlet connected with said receiver and for compressing the gas, a storage tank for compressed gas in vapor phase and normally connected with the discharge of said compressor, a condenser cooled by a refrigerant, a container for liqueied fermentation gas discharged from said condenser, mechanism responsive to pressures in said vapor storage tank and including valves, one of which is normally open when p-ressure in said storage tank is low to admit gas from said compressor to said vapor storage tank and which is closed by said mechanism when said pressure reaches the desired maximum, the other of said valves being normally closed and being opened by said mechanism when said first valve is closed, to admit compressed gas to said condenser for delivery in liquid phase to said liquid container, a valve controlled passage connecting the upper portion of said liquid storage container and delivering vapor from said container to said vapor storage tank when the pressure in said liquid container becomes excessive, and another valve controlled passage connecting said vapor storage tank with said receiver when the pressure in said vapor storage tank becomes excessive, whereby gas discharged irom said vapor storage tank is again liquefied and returned to said liquid storage container.

18. Apparatus for handling fermentation gas including a receiver for said gas at low pressure, a compressor having its inlet connected with said receiver and for compressing the gas, a storage tank for compressed gas in vapor phase and normally connected with the discharge of said compressor, a condenser cooled by a refrigerant, a container' for liquefied fermentation gas discharged from said condenser, mechanism responsive to pressures in said vapor storage tank and including valves, one of which is normally open when pressure in said storage tank is low to admit gas from said compressor to said vapor storage tank and which is closed by Said mechanism when said pressure reaches the desiredV maximum, the other of said valves being normally closed and being opened by said mechanism when said iirst valve is closed, to admit compressed gas to said condenser for delivery in liquid phase to said liquid container, a pressure controlled switch which is closed when pressure in said liquid com tainer falls below a desired mi -imum, and means controlled by said switch to actuate said mechanism to supply compressed gas to said condenser.

FRANCIS A. CRAIG.

References Cited in the le of this patent UNITEDVSTATES PATENTS Number Name Date 518,361 Zwietusch Apr. 17, 1854 2,082,189 Twomey June 1, 1937 2,239,485 Markus et al Apr. 22, 1941 2,333,154 Markus et al Nov, 2, 1943 2,601,764 Collins et al. July 1, 1952 

